The Rev. Al Sharpton – who was unwelcome at City Hall under Mayor Giuliani – has been invited to the inauguration of Mayor-elect Bloomberg and other city officials, The Post has learned.

Sharpton said his inclusion on the 3,000-person guest list – courtesy of Comptroller-elect Bill Thompson- is a signal that communities of color will have access to the incoming administration.

Sharpton said he’s not yet sure he’ll be able to attend the gala ceremony on the steps of City Hall because he has a previous commitment in Detroit.

Former President Bill Clinton, Sens. Hillary Clinton and Chuck Schumer and other dignitaries are expected.

For eight years, Sharpton has not set foot on the side of City Hall where Giuliani has his offices.

Bloomberg, a Democrat-turned-Republican, raised eyebrows when one of the first people he went to meet after his upset victory over Mark Green last month was Sharpton.

A Bloomberg spokesman made it clear that Sharpton was a guest of Thompson – and not the mayor-elect.

Sharpton also will be on hand the night of Dec. 31 for the midnight swearing-in bash of Thompson at a downtown restaurant.

Thompson – the second African-American to win citywide office, after former Mayor David Dinkins – will be sworn in by his father, a retired state Supreme Court justice from Brooklyn.

Public Advocate-elect Betsy Gotbaum will host friends and family at a private swearing-in dinner party at an Upper West Side apartment. She will be sworn in by Dinkins, with former Mayor Ed Koch in attendance.

Both Thompson and Gotbaum will then join Bloomberg for the public festivities on Tuesday afternoon.

Among Gotbaum’s guests will be philanthropists Lewis and Dorothy Cullman, the Rev. Calvin Butts, the Rev. Floyd Flake and designer Oscar de la Renta.

All three newly elected officials will host a wine-and-cheese reception at the renovated Tweed Courthouse later in the afternoon.

Bloomberg’s mother turns 93 the following morning, and he is expected to hold a more elaborate private celebration for her.